Low friction shielded bearing assembly

Abstract

A low friction shielded bearing assembly for supporting a machine shaft, for example a spindle shaft of a food cutting machine, includes a rolling element radial and thrust bearing subassembly containing ball or roller elements supported between inner and outer relatively rotatable bearing races with seal elements for retaining lubricant within the bearing subassembly. A flanged, fretting and corrosion resistant sleeve is fixed within the inner race of the bearing subassembly with the flange of the sleeve shielding an adjacent bearing seal against direct impingement by sprayed cleaning fluids. The sleeve also transmits radial and thrust loads to the inner race. The bearing subassembly is retained within an annular retainer that is adjustably attached to a machine frame to permit adjustment of the location of the rotational axis of a shaft supported by the bearing and to permit adjustment of the bearing location axially along the shaft and relative to the machine frame. A secondary journal bearing may be provided as a backup to the ball or roller bearing subassembly in the event of a failure of the rolling element bearing and also to enable alignment of a shaft during assembly and disassembly of the shaft relative to the bearing assembly. The journal bearing normally does not contact the shaft during normal operation of the bearing assembly.

We claim: 
     
       1. A low friction shielded bearing assembly comprising: a sealed rolling element radial and thrust bearing including an assembly of rolling elements between relatively rotatable inner and outer annular bearing races and a lubricant seal extending between the races, the lubricant seal including at least one seal portion fixedly secured to the outer bearing race and extending radially into close proximity with the inner bearing race on one side of said rolling elements;   said inner bearing race including an inner peripheral surface centered about an axis of rotation;   a retainer engaging and holding the outer bearing race against rotation;   a shield and thrust sleeve concentrically fixedly secured to and coextensive with the inner bearing race inner peripheral surface, the sleeve including a sleeve inner peripheral surface adapted to receive an outer diameter of a rotary shaft to be supported by the bearing assembly in close fitting relationship;   said sleeve including a flange located to one side of the bearing assembly and extending radially relative to said axis of rotation to a position whereat the flange overlies at least the juncture between the at least one seal portion and the inner bearing race in close proximity to said at least one seal portion, said flange including a radially extending thrust load receiving surface on the side of the flange opposite the bearing assembly;   whereby said sleeve rotates with the inner bearing race relative to the outer bearing race and outer seal portion, transmits rotary motion, axial thrust loads and radial loads to the inner bearing race and shields at least the juncture between the outer seal portion and the inner race from direct impingement of fluid approaching the outer seal portion from the direction of the flange location.   
     
     
       2. The bearing assembly according to claim 1, wherein said retainer comprises an axially extending annular housing and at least one axial locating surface for axially locating the bearing outer race in the housing. 
     
     
       3. The bearing assembly according to claim 2, said shield and thrust sleeve inner peripheral surface having a first inner diameter; an annular journal bearing retained in said retainer housing and fixed against rotation relative to the housing, said journal bearing including an inner annular bearing surface having a second inner diameter greater than said first inner diameter and centered about said axis of rotation;   said journal bearing disposed adjacent the side of said radial and thrust bearing opposite the side thereof on which said sleeve flange is located.   
     
     
       4. The bearing assembly according to claim 3, wherein said annular housing includes an inner peripheral surface larger in radial size than said journal bearing, and including an annular spacer element secured in said housing between said journal bearing and the housing inner peripheral surface; said journal bearing fixedly secured to said spacer. 
     
     
       5. The bearing assembly according to claim 4, including a second seal portion fixedly secured to the outer bearing race and extending into close proximity with the inner bearing race, said second seal portion located towards the side of said rolling elements that is opposed to the side toward which the at least one seal portion is located; said spacer element overlying the juncture between said second seal portion and said inner bearing race.   
     
     
       6. The bearing assembly according to claim 2, wherein said axial locating surface extends radially inwardly over at least a part of said at least one seal portion and in close proximity with a radial periphery of said flange. 
     
     
       7. The bearing assembly according to claim 1, wherein said radial and thrust bearing assembly comprises a sealed lubricated ball bearing assembly. 
     
     
       8. The bearing assembly according to claim 1, wherein said shield and sleeve is formed of a non-metallic material resistant to fretting and corrosion in an operational environment of the bearing assembly. 
     
     
       9. The bearing assembly according to claim 8, wherein said shield and thrust sleeve is formed of a plastic bearing material. 
     
     
       10. A low friction shielded bearing assembly for supporting a machine shaft against radial and axial thrust loads, comprising: a rotatable machine shaft including a first outer bearing cooperating surface on one portion thereof, said first outer bearing cooperating surface having an outer diameter;   a thrust load transmitting member connected to the shaft for rotation therewith and including a radially extending thrust load applying surface;   a sealed rolling element radial and thrust bearing including an assembly of rolling elements between relatively rotatable inner and outer annular bearing races and a lubricant seal extending between the races, the lubricant seal including at least one seal portion fixedly secured to the outer bearing race and extending radially into close proximity with the inner bearing race on one side of said rolling elements;   said inner bearing race including an inner peripheral surface centered about an axis of rotation;   a retainer engaging and holding the outer bearing race against rotation;   a shield and thrust sleeve concentrically fixedly secured to and coextensive with the inner bearing race inner peripheral surface, the sleeve including a sleeve inner peripheral surface;   said sleeve including a flange located to one side of the bearing assembly and extending radially relative to said axis of rotation to a position whereat the flange overlies at least the juncture between the at least one seal portion and the inner bear race in close proximity to said at least one seal portion, said flange including a radially extending thrust load receiving surface on the side of the flange opposite the bearing assembly;   said machine shaft first outer bearing cooperating surface located concentrically within said sleeve inner peripheral surface in close fitting relationship and arranged to rotate with said sleeve;   said thrust load applying surface of said thrust load transmitting member located adjacent the thrust load receiving surface of said flange.   
     
     
       11. The bearing assembly according to claim 10, wherein said retainer comprises an axially extending annular housing and at least one axial locating surface for axially locating the bearing outer race in the housing. 
     
     
       12. The bearing assembly according to claim 11, said shield and thrust sleeve inner peripheral surface having a first inner diameter; an annular journal bearing retained in said retainer housing and fixed against rotation relative to the housing, and including an inner annular bearing surface having a second inner diameter greater than said first inner diameter centered about said axis of rotation;   said journal bearing disposed adjacent the side of said radial and thrust bearing opposite the side thereof on which said seal flange is located;   said shaft having a second bearing cooperating surface extending through said inner annular bearing surface, said second bearing cooperating surface being smaller in diameter than said second inner diameter of said inner annular bearing surface.   
     
     
       13. The bearing assembly according to claim 12, wherein said first and second bearing cooperating surfaces of said shaft have the same diameter. 
     
     
       14. The bearing assembly according to claim 12, wherein said retainer includes an inner peripheral surface larger in radial size than said journal bearing, and including an annular spacer element secured in said housing between said journal bearing and the housing inner peripheral surface; said journal bearing fixedly secured to said spacer. 
     
     
       15. The bearing assembly according to claim 14, including a second seal portion fixedly secured to the outer bearing race and extending into close proximity with the inner bearing race, said second seal portion located towards the side of said rolling elements that is opposed to the side toward which the at least one seal portion is located; said spacer element overlying the juncture between said second seal portion and said inner bearing race.   
     
     
       16. The bearing assembly according to claim 11, wherein said axial locating surface extends radially inwardly over at least a part of said at least one seal portion and in close proximity with a radial periphery of said flange. 
     
     
       17. The bearing assembly according to claim 11, including an adjustable bearing assembly holder engaging the retainer, said holder including an axial adjustment device enabling axial position adjustment of the retainer relative to the shaft when the shaft is substantially axially fixed. 
     
     
       18. The bearing assembly according to claim 17, including a fixed machine frame element; said shaft extending through said frame element   said holder including a radial adjustment device enabling radial adjustment of the retainer, bearing assembly and shaft relative to the machine frame element.   
     
     
       19. The bearing assembly according to claim 10, wherein said radial and thrust bearing assembly comprises a sealed lubricated ball bearing assembly. 
     
     
       20. The bearing assembly according to claim 10, wherein said shield and thrust sleeve is formed of a non-metallic material resistant to fretting and corrosion in an operational environment of the bearing assembly. 
     
     
       21. The bearing assembly according to claim 20, wherein said shield and thrust sleeve is formed of a plastic bearing material.